1. What is Critical Depth of Rectangular Channel?

The Critical Depth of Rectangular Channel is defined as the depth of flow where energy is at a minimum for a particular discharge. It represents the specific energy condition where the flow transitions between subcritical and supercritical states.

2. How Does the Calculator Work?

The calculator uses the critical depth formula:

Where:

• \( h_r \) — Critical Depth of Rectangular Channel (m)
• \( E_r \) — Critical Energy of Rectangular Channel (m)

Explanation: The formula establishes the relationship between critical energy and critical depth in rectangular open channel flow, where the critical depth is exactly two-thirds of the critical energy.

3. Importance of Critical Depth Calculation

Details: Calculating critical depth is essential for hydraulic engineering design, flood control analysis, and understanding flow behavior in open channels. It helps determine when flow transitions between different regimes and assists in designing efficient channel sections.

4. Using the Calculator

Tips: Enter the critical energy value in meters. The value must be positive and greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the physical significance of critical depth?
A: Critical depth represents the depth at which the specific energy is minimum for a given discharge in an open channel. At this depth, the flow velocity equals the wave velocity.

Q2: How does critical depth relate to Froude number?
A: At critical depth, the Froude number equals 1. When depth is greater than critical (subcritical flow), Fr < 1, and when depth is less than critical (supercritical flow), Fr > 1.

Q3: Can this formula be used for non-rectangular channels?
A: No, this specific formula applies only to rectangular channels. Other channel shapes (trapezoidal, circular, triangular) have different relationships between critical energy and critical depth.

Q4: What are practical applications of critical depth calculation?
A: Critical depth calculations are used in designing hydraulic structures like weirs, flumes, spillways, and in analyzing flow conditions in natural streams and engineered channels.

Q5: How does channel slope affect critical depth?
A: Critical depth is independent of channel slope and roughness. It depends only on the discharge and channel geometry for a given cross-section.